1 #include <iostream>
 2 #include <cstdio>
 3 #include <algorithm>
 4 using namespace std;
 5 typedef long long ll;
 6 ll n,m,r;
 7 struct node
 8 {
 9     ll start;
10     ll end;
11     ll p;
12 };
13 node a[1005];
14 ll dp[1005];
15 bool cmp(const node & a,const node & b)
16 {
17     if(a.start != b.start)
18     {
19         return a.start < b.start;
20     }
21     return a.end < b.end;
22 }
23 ll solve()
24 {
25     for(int i = 0;i < m;i ++)
26     {
27         dp[i] = a[i].p;
28         for(int j = 0;j < i;j ++)
29         {
30             if(a[j].end <= a[i].start)
31                 dp[i] = max(dp[i], dp[j] + a[i].p);
32         }
33     }
34     ll maxn = 0;
35     for(int i = 0;i < m;i ++)
36         maxn = max(maxn, dp[i]);
37     return maxn;
38 }
39 int main()
40 {
41     cin >> n >> m >> r;
42     for(int i = 0;i < m;i ++)
43     {
44         scanf("%lld%lld%lld",&a[i].start,&a[i].end,&a[i].p);
45         a[i].end += r;
46     }
47     sort(a, a + m,cmp);
48     cout << solve() << endl;
49     return 0;    
50 }